High-nickel positive electrode active material, producing method thereof, positive electrode and lithium secondary battery comprising the same

Abstract

A method for producing a high-nickel positive electrode active material, a positive electrode active material produced thereby, and a positive electrode and a lithium secondary battery including the same is provided. The method includes preparing a lithium composite transition metal oxide having a nickel content of 80 atm % or greater among transition metals, washing the lithium composite transition metal oxide, and mixing the washed lithium composite transition metal oxide with an aluminum raw material and heat treating the mixture at a temperature of 650° C. to 690° C. to obtain a positive electrode active material having a surface portion doped with aluminum.

The invention claimed is: 
     
       1. A method for producing a high-nickel positive electrode active material, comprising:
 preparing a lithium composite transition metal oxide having a nickel content of 80 atm % or greater among transition metals; 
 washing the lithium composite transition metal oxide; and 
 mixing the washed lithium composite transition metal oxide with an aluminum raw material and heat treating the mixture at a temperature of 650° C. to 690° C. to obtain a positive electrode active material having a surface portion doped with aluminum, 
 wherein the lithium composite transition metal oxide is represented by [Formula 1] below:
   Li x Ni y Co z Mn w Al v M u O 2   [Formula 1]
 
 
 in Formula 1, M is one or more selected from the group consisting of W, Cu, Fe, Ba, V, Cr, Ti, Zr, Zn, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and 0.9≤a≤1.5, 0.8≤b<1.0, 0<c<0.2, 0<d<0.2, and 0≤e≤0.02. 
 
     
     
       2. The method of  claim 1 , wherein the aluminum raw material comprises an aluminum-containing acetate, an aluminum-containing nitrate, an aluminum-containing sulfate, an aluminum-containing halide, an aluminum-containing sulfide, an aluminum-containing hydroxide, an aluminum-containing oxide, an aluminum-containing oxyhydroxide, or a mixture thereof. 
     
     
       3. The method of  claim 1 , wherein the aluminum raw material is mixed in an amount of 0.05 parts by weight to 1 parts by weight based on 100 parts by weight of the washed lithium composite transition metal oxide. 
     
     
       4. The method of  claim 1 , wherein the heat treatment is performed in an oxygen atmosphere. 
     
     
       5. The method of  claim 1 , wherein the mixing is dry-mixing. 
     
     
       6. The method of  claim 1 , wherein the M is a doping element substituted for a transition metal site of the lithium composite transition metal oxide. 
     
     
       7. A high-nickel positive electrode active material having an average composition represented by Formula  2  below:
   Li x Ni y Co z Mn w Al v M u O 2   [Formula 2]
 
 in Formula 2, M is one or more selected from the group consisting of W, Cu, Fe, Ba, V, Cr, Ti, Zr, Zn, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and 0.9≤x≤1.5, 0.8≤y<1.0, 0<z<0.2, 0<w<0.2, 0.001≤v≤0.05, and 0≤u≤0.02, 
 wherein a doping concentration of Al gradually decreases from a surface of the positive electrode active material toward the center thereof, and 
 wherein an atomic fraction of Al in all transition metals is 2 atm % or greater at a depth of 50 nm or less from the surface of the positive electrode active material. 
 
     
     
       8. The high-nickel positive electrode active material of  claim 7 , wherein the atomic fraction of Al in all transition metals is 2 atm % to 15 atm % at a depth of 50 nm or less from the surface of the positive electrode active material. 
     
     
       9. A positive electrode comprising the high-nickel positive electrode active material of  claim 7 . 
     
     
       10. A lithium secondary battery comprising the positive electrode of  claim 9 . 
     
     
       11. The high-nickel positive electrode active material of  claim 7 , wherein the M is a doping element substituted for a transition metal site of the lithium composite transition metal oxide.